Connection rod for screw or hook polyaxial system and method of use

ABSTRACT

A low-profile surgical implant assembly is provided that includes a connector device that is an integral part of a rod, the connector device allowing the rod to be attached directly to a bone screw, such as a pedicle screw. Another aspect of the invention is a clamp device that allows the length of a rod spanning to attachment devices to be adjusted at the time of implantation, and further allows the clamp device to be secured by tightening a securing end of the clamp at the attachment device. The assemblies are useful for insertion into bone and connecting a foreign object to bone via a polyaxial coupling mechanism. A method for implanting the assembly is also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.10/262,574 filed on Sep. 30, 2002 and entitled “CONNECTION ROD FOR SCREWOR HOOK POLYAXIAL SYSTEM AND METHOD OF USE”, which claimed priority fromU.S. Provisional Patent Application No. 60/325,809 filed Sep. 28, 2001.The entire disclosures of these applications are considered to be partof the disclosure of the present application and are hereby incorporatedby reference in their entirety.

FIELD OF THE INVENTION

This invention relates generally to an adjustable rod for stabilizing aportion of the spine, or two or more bone segments and a method of usingthe same. More specifically, the device and method include a series ofcomponents that provide a low-profile configuration when assembled,thereby minimizing tissue displacement and interference with nearbyjoint articulation.

BACKGROUND OF THE INVENTION

The use of fixation devices for the treatment of vertebrae deformitiesand injuries is well known in the art. Various fixation devices are usedin medical treatment to correct curvatures and deformities, treat traumaand remedy various abnormal spinal conditions. Treatment of theseconditions generally requires the implantation of various componentpieces such as support rods, crosslinks, caudal facing hooks, cranialfacing hooks and like components, which form a spinal implant system.

It is necessary in spinal implant systems to properly anchor the systemto bone to provide necessary support of the implant. Bone screws arecommonly used for anchoring spinal implant systems. However, there areseveral problems with the use of fixed screws for anchoring spinalimplants. The exact final position of a bone screw is difficult, if notimpossible, to predict prior to the exposure of the patient's bone. Thisunpredictability results from the uncertainty of exact bone formationand shape within an individual patient. Additionally, it can bedifficult to predetermine the structure of the bone, i.e. whether thebone is soft or even osteoporotic. Even if the final position of thescrew can be predetermined, the necessary shape and position of a spinalrod implant may create unwanted stress upon the bone screw or the boneitself. This is especially true where a plurality of screws is requiredalong the spinal column for securement of an implant. The alignment ofthe rod with several screws along the vertebrae compounds this problemand makes undesired stress much more probable. Moreover, thismisalignment may influence the extent and speed of correction of thespinal defect.

It is thus desirable to have a polyaxial securement method. There existsa number of patents drawn to polyaxial bone screws. Unfortunately, theadvantage of many of these designs comes at the expense of bulk in theconnection means or complexity of implantation. Such devices includedcomplicated retention collets or securing systems that eliminate thedevice from functioning as a polyaxial system. In addition, as the sizeof a bone screw increases, so too does the displacement of normal bodilyformations, such as muscular tissue or bone. It is common in theinsertion of spinal implants to necessarily remove portions of vertebralbone to allow proper insertion of a bone screw. Moreover, this bulk mayresult in long-term muscular displacement that may lead to a patient'spain or discomfort.

Increased complexity of the installation procedure is undesirablebecause it increases a patient's time in surgery. Increased operatingtime is known to increase the risk of many complications associated withsurgery. The additional time necessary to remove, or even temporarilydislocate, bone or muscular tissue also increases operating time, andthus the risk of complications.

In addition, the prior art fails to provide a low-profile multi-piececonnector that includes poly-axial adjustability and that can be used toaccommodate a variety of geometry requirements that may arise forcertain patients. Therefore, a need exists to provide a low-profilemulti-piece connector that can be adapted to a variety of geometryrequirements.

The prior art also fails to provide a tool for implantation of anattachment device that has an entry channel for a tension link, or thatotherwise has an expansion slot. Thus, a need exists for a tool thatfittingly accepts the head of a attachment device that has a hollow corewith either an entry channel and/or at least one expansion slot, andthat can be used to accept and drive into bone the attachment device.

In addition to the above noted shortcomings of the prior art, the priorart also fails to provide a low-profile device that includes a connectorthat can be positioned at the very end of a stabilizing rod, therebyproviding a device that does not disturb the adjacent vertebra. Morespecifically, the connectors of the prior art require attachment to therod with a section of rod extending beyond the connector itself.Accordingly, a need exists to reduce or otherwise minimize the length ofrod run-out beyond the end connector to prevent interference with thearticulation of the neighboring vertebrae.

The prior art also fails to provide a low-profile device that allows therod length to be easily adjusted during implantation with a minimalamount of effort by the installing surgeon. More particularly, where twobone segments, such as a first vertebra and a second vertebra, are beingbridged by existing devices, the rod typically extends beyond theconnector, and needs to be specifically chosen or otherwise cut toaccommodate the dimensions of the subject patient. Therefore, a needexists to provide an adjustable length rod implantation assembly thatcan be installed relatively easily by a surgeon, and that further has anability to be adjusted at the moment of implantation to therebyaccommodate the geometry requirements of the patient. In addition, aneed exists for an extended shaft to a tension link that can thereby actas a guide or leader for installation of a number of the assemblycomponents. Such a device can serve to simply the installation processand minimize the size of the incision necessary to access the patient'sinterior surgical site.

The prior art also fails to provide a rod implant that can betelescopically adjusted at the time of implantation. Such a device isneeded to further accommodate the individual patient's requirements thatexist and that are encountered upon performing and incision andencountering in situ conditions.

It is also desirable with some patients to have a spinal implant systemthat allows the vertebral column to settle naturally under the weight ofthe human body. Human bone heals more readily under some pressure. In arigid spinal implant system, the patient's spinal column may beunnaturally held apart by the structure of the implant. It is possiblethat this stretching of the vertebrae, in relation to one another,results in delayed or incomplete healing of the bone.

In view of the above, there is a long felt but unsolved need for amethod and system that avoids the above-mentioned deficiencies of theprior art and that provides an effective system that is relativelysimple to employ and requires minimal displacement or removal of bodilytissue.

SUMMARY OF THE INVENTION

In accordance with the present invention, a polyaxial attachment deviceis provided with a socket for receiving a headed connecting link. Asurgical implant assembly employing the polyaxial attachment device isalso disclosed. The surgical implant assembly of the present inventionincludes an attachment device, a headed anchor shaft (or tension link),a connector formed as an integral part of a first stabilizing rod, and aclamp device that grasps the first stabilizing rod while also attachingto a second attachment device using a second interconnecting mechanism,such as a tension link.

The attachment device of the present invention has a shank with asecurement mechanism on one end and an enlarged area on the other end.The securement mechanism may be selected from any known method ofsecuring one article to another, for example, a hook, a plate, a flangeddevice, or an adhesive, however, it is anticipated that the most commonsecurement mechanism used will be screw threads. The enlarged areaincludes a hollow core, i.e., a socket, and a central aperture providingaccess to the hollow core. The enlarged area need only be large enoughto envelop the head of the tension link and provide a wall thicknessnecessary for strength considerations.

The attachment device may include additional features to enable theinsertion of the head end of the tension link into the hollow core. Theenlarged area of the attachment device may include an entry channelleading to the hollow core that accommodates the tension link head endso that the tension link may be advanced, shaft end first, until thehead of the tension link is positioned within the hollow core.Additionally, the entry channel and the central aperture may beconnected by a slot through the wall of the enlarged area. In this way,the tension link head end may be positioned within the hollow corewithout extending the entire length of the tension link beyond theenlarged area of the attachment device opposite the central aperture.The surgeon may place only the head end of the tension link at the entrychannel, slide the tension link shaft through the tension link slot, anddraw the head end into the hollow core. Alternatively, in lieu of anentry channel or tension link slot, the enlarged area may include one ormore expansion slots. In this embodiment, the head of the tension linkmay be inserted into the hollow core through the central aperture by theapplication of enough force to expand the central aperture. Once thehead of the tension link is properly received into the hollow core, theenlarged area returns to its original size and shape. Unwanted expansionof the enlarged area is prevented by the connector once the enlargedarea is properly seated into a head receptacle on the connector duringimplantation. This maintains the head of the tension link within thehollow core.

The external surface of the enlarged area of the attachment device maybe formed into one of limitless geometries. For example, the externalsurface may be spherical, or at least semi-spherical. The externalsurface may be at least slightly aspheric. By controlling the degree ofasphericity, the contact surface between the attachment device and theconnector can thereby control the degree of freedom of the connectorrelative to the attachment device. Alternatively, the external surfacemay be conical, or a truncated cone shape, to allow rotational freedomwhile maintaining a coaxial relationship between the attachment deviceand the connector. Also, the external surface may be polyhedral orprovided with facets to allow angular displacement in only finite stepsor prevented altogether. In embodiments including conical, truncatedcone shape, polyhedral or faceted geometries of the external surface ofthe enlarged area, the mating head receptacle of the connector may havecorresponding geometry.

The tension link secures and maintains the position of the connectorrelative to the attachment device. The tension link is a shaft with ahead end and a thread end. The head end, as described above, iscontained within the hollow core of the attachment device. The threadedend extends through the connector and is secured to the connector by atension link nut (herein also referred to as a “link nut”) threaded ontothe thread end.

The tension link may be provided with a projection to preventundesirable rotation of the link when tightening or loosening the linknut, yet still enable angular displacement necessary to provide apolyaxial connection. In one embodiment, a link retainer, or aprojection, may be provided on the shaft of the tension link. In thisembodiment, it is necessary to provide a link retainer recess within thetension link cavity of the connector. In an alternative embodiment, thelink retainer, or projection, may be provided at the intersection of thetension link shaft and the head end, and extending over a portion of thesurface of the head end. In this embodiment, used with the attachmentdevice embodiment including a tension link slot, the rotation may beprevented by contacting the link retainer with one side of the tensionlink slot. In either of the two foregoing embodiments, it is desirableto undersize the link retainer, relative to the link retainer recess orthe tension link slot, so that the polyaxial freedom of the tension linkand attachment device combination is not unduly limited. In analternative embodiment, a retaining process, or small projection, may beprovided on the tension link head. The retaining process should bepositioned such that the retaining process is within the entry channel.Undesired rotation may be prevented by contacting the small projectionwith the wall of the entry channel.

The connector couples the attachment device to the implant component,such as a spinal rod implant. One type of connector described herein hasa connecting end with a head receptacle, a rod end with a rod aperture,and a tension link cavity. The tension link, with its head positioned inthe hollow core of the attachment device, is inserted through thetension link cavity so that an enlarged area of the attachment devicenests in the head receptacle. The rod aperture secures the implantcomponent in a desired position. The rod aperture may be secured by thetension link when the link nut is threaded and tightened on the link. Inthis embodiment, the rod end of the connector has a gap on one side ofthe rod aperture. The tension link cavity extends continuously throughthe tension link on both sides of the gap. The upper portion of the rodend forms a tab. As the tab is drawn toward the receiver end of theconnector the gap narrows until the rod aperture firmly clamps theimplant component or until the gap is drawn completely together.

In still other embodiments, it may also be desirable to provide aseparate system for securing the connector to the attachment device andfor securing the implant component to the connector. Therefore, in analternative embodiment, the gap is connected to the rod aperture in aposition that does not intersect the rod aperture. In this embodiment, aseparate screw, or other connection device, is required to secure theimplant component in the rod aperture. The tension link is then used tosecure the connector to the attachment device.

In either of the two foregoing connector embodiments, it may bedesirable to secure the rod within the rod aperture without clamping tothe extent axial movement of the rod within the rod aperture isprevented. In this way, for example, the spine may settle under its ownweight and provide a better healing environment for the bone. Inconjunction with this embodiment, the implant component may be suppliedwith flanges, or other extensions to constrain axial movement of theimplant component within a desired range.

To surgically implant a device of the present invention, the surgeon mayattach an attachment device, selected from one of the embodiments of thepresent invention. After successful attachment, the surgeon may insert atension link of the present invention by positioning the head end of thetension link within the hollow core of the attachment device. Thesurgeon may then place a connector, with a head receptacle designed formating with the second end of the attachment device, upon the attachmentdevice by inserting the tension link through the tension link cavity ofthe connector. At this point, the surgeon may select the desired angleof position of the connector for attaching a implant component. Once theconnector is properly adjusted, the link nut may be secured to thetension link, thereby securing the elements together in the desiredposition. The link nut may be loosened, as necessary, to readjust theplacement of the implant component. Alternatively, if a connector havinga separate implant component securement device is used, the step ofsecuring the link nut may be delayed until after the implant componentis secured in the rod aperture and properly positioned.

Based on the foregoing summary, a number of worthwhile aspects of thepresent invention can be readily identified. An attachment device isprovided with a small and simple polyaxial adjustment mechanism. Theminimal size of the enlarged area of the attachment device allowsattachment of the device to human bone without significant displacementof human tissue. Therefore, the complexity of surgery and the followingpain and discomfort of the patient may be minimized. The polyaxialnature of the device, combined with the small size, may allow a surgeonto attach the securement device to a secure portion of the human bodywithout the need to remove bony processes to accommodate a largerattachment device. Additionally, a simple surgical implant assembly,including the polyaxial attachment device, is provided. The simplicityof the elements, and the assembly process thereof, may reduce thepatient's time in surgery, thus reducing the risk and probability ofsurgical complications. Finally, a number of embodiments of the presentinvention may be used in combination to allow the surgeon great latitudein selection of materials. The surgeon may select from differentembodiments of the attachment device, the tension link, and theconnector to best fit the surgical implant parameters. With thesechoices the surgeon may then best determine which embodiments of whichelements to select to minimize removal or displacement of bodily tissueor bone, and thereby reduce both the patient's risk of surgicalcomplications and post-surgical pain and discomfort.

A significant feature of the present invention is the ability to providea construct used to stabilize the spine or a portion thereof. Theconstruct utilizes a single tension link nut to tighten down thestructure at each bone screw (also referred to herein as an attachmentdevice) location. More particularly, the present invention utilizes abone screw or attachment device that possesses threads at one end alonga shaft and an enlarged head with a hollow core at the other end. Thethreads are used to secure the bone screw to bone. The enlarged head ofthe bone screw includes an entry channel, tension link slot, or boththat allows the shaft of the tension link to be fed up through the entrychannel or tension link slot. In addition, the hollow core is shaped toreceive the head of a tension link. The enlarged area of the bone screwpossesses an aperture that is sized to permit the shaft of the tensionlink to pass through it, while retaining the head of the tension link.The shaft of the tension link is then fed through a connector. Theconnector is a component that possesses a separate aperture to receive astabilizing rod. A tension link nut is then secured to the end of thethreaded tension link shaft, thereby securing the connector to thetension link and bone screw.

In a separate aspect of the invention, a tool is provided to insert theattachment device. The tool includes a head portion that cooperates withthe structural features of the attachment device. More specifically, thehead portion of the tool includes a projection to mate with the hollowcore, and/or the expansion slot, and/or the entry channel of theattachment device. The tool is rotated to force the threads of theopposite end of the attachment device to advance into the target bonesegment. After the attachment device is inserted, the tool is disengagedfrom the attachment device thereby leaving the attachment deviceinstalled.

In an another embodiment of the invention, a multi-piece connector isprovided that allows additional adjustability of the connector device.The multi-piece connector includes use of the attachment device having ahollow core and a tension link that includes a head that is fitted intothe hollow core. A first piece of the multi-piece connect is attached byfeeding the shaft of the tension link through an opening in the firstpiece. The implant rod is then positioned proximate the first piece andadjacent a cam portion of the first piece. The second piece of themulti-piece connector is then positioned over the implant rod by againpassing the shaft of the tension link through an opening in the secondpiece. Finally, after adjusting the desired angle of the multi-piececonnector by rotating the tension link within the attachment device, alink nut is then applied to the threaded end of the shaft of the tensionlink thereby tightening the nut against the connector and the enlargedhead of the attachment device.

In an alternate embodiment, a connector is formed in the implant roditself. In this embodiment, the rod possesses a receptacle that is asocket, such that the ball of the enlarged area of the attachment devicewith the head of the tension link in place, fits into the socket that isan integral part of the rod. Thus, a ball-and-socket arrangement isformed providing a polyaxial connector within the rod itself. A tensionlink nut is then secured to the end of the threaded shaft of the tensionlink, thereby securing the rod to the bone screw. When positioned at theend of a rod, this is a very low profile configuration that minimizesthe length of the incision that is necessary to perform the surgery.Furthermore, a mechanical advantage is gained by the interaction of thecomponents as previously described. Specifically, strength of the finalconnection is not simply attributable to the tightening of the tensionlink nut, but is also attributable, in part, to the placement of thehead of the tension link within the hollow core of the bone screw, orattachment device. In so doing, the head of the tension link causes aslight expansion of the hollow core, much like how a wedge is used tosecure an axe head at the top of an axe handle. The enlarged area of thescrew is in turn partially encompassed by the receptacle socket of therod itself.

In yet a separate aspect of the invention, a clamp device is furnishedfor providing an adjustable rod structure for implantation. In oneembodiment of the clamp, the clamp includes a lower clamp portion and anupper clamp portion. The lower clamp portion has a clamp region thatcooperates with a clamp region on the upper clamp portion. At a spaceddistance from the clamp regions, the lower clamp portion has a securingend that cooperates with a securing end on the upper clamp portion. Thelower and upper clamp portions are used in combination with an interiorrod member that is grasped by the clamp regions of the lower and upperclamp portions when the securing ends of the lower and upper clampportions are brought into a tight mating configuration. Morespecifically, the securing ends of the lower and upper clamp portionsinclude receptacles that have sockets that mate with each other and thatalso mate with the enlarged area of an attachment device.

A method of use is also presented for the clamp device, wherein in apreferred embodiment the two attachment devices are installed byadvancing an attachment device into each of two bone segments. Thehollow core of each attachment device is then fitted with a the head ofa tension link. Alternately, the tension link may be inserted into thehollow core of the tension link prior to insertion of the attachmentdevices into bone. After the attachment devices with their respectivetension links are in place, one of the attachment devices is fitted withan interior rod member that includes a rod portion and an end connectorin the form of a receptacle shaped like a socket. The socket includes atension link cavity such that the shaft of the tension link is passedthrough the tension link cavity as the socket is being placed over theenlarged area of the first attachment device. A clamp comprising a lowerand upper clamp portion is then assembled to grasp the rod portion ofthe interior rod member as the upper and lower clamp are connected tothe second attachment device by passing the shaft of the second tensionlink through tension link cavities in the securing ends of the lower andupper clamp portions. Link nuts are then threaded on to exposed ends ofthe tension link shafts and are tightened. The position of the interiorrod member can be adjusted within the clamp as the link nuts aretightened, thereby allowing the surgeon to adjust the size of theassembly to accommodate the patient's needs for a customized fit. Theassembly minimizes the need to create a large incision becauseimplantation work can be substantially performed from a directionperpendicular to the bone segments. Furthermore, this low profileassembly is relatively simple to install, thereby reducing surgery timeover existing stabilizing devices.

In a separate aspect of the invention, a telescoping rod is providedthat allows adjustability of the rod. The telescoping rod includes aninner and an outer member that cooperate to allow the surgeon to adjustthe length of the rod to span two attachment devices. A set screw may beused with this embodiment to interlock the inner and the outer rodmembers.

In yet a separate aspect of the invention, the tension links may includean extended shaft that serve as guides for lowering and/or installingimplantation components over and onto the attachment devices. Afteracting as guides for the lowering of implantation components over theattachment devices, link nuts are guided to the thread portions of thetension links. The extended shafts are subsequently removed by ashearing tool, by breaking the extended shaft portion away from thetension link along a pre-existing score location, or by otherappropriate means.

Additional advantages of the present invention will become readilyapparent from the following discussion, particularly when taken togetherwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a partial cross-sectional view of one embodiment of theattachment device of the present invention;

FIG. 1 b is an end perspective view of an alternative embodiment of theattachment device of the present invention;

FIG. 2 is an end perspective view of an alternative embodiment of theattachment device of the present invention;

FIG. 3 is a cross-sectional view of the attachment device shown if FIG.2;

FIG. 4 is an end perspective view of another alternative embodiment ofthe attachment device of the present invention;

FIG. 5 is a top plan view of the attachment device shown in FIG. 4;

FIG. 6 is an end perspective view of yet another alternative embodimentof the attachment device of the present invention;

FIG. 7 is an end perspective view of still another alternativeembodiment of the attachment device of the present invention;

FIG. 8 is an elevation view of the attachment device shown in FIG. 7;

FIG. 9 a is an front elevation view of one embodiment of the tensionlink with a link retainer of the present invention;

FIG. 9 b is a side elevation view of the tension link with link retainershown in FIG. 7 a;

FIG. 9 c is an end view of the tension link with link retainer shown inFIG. 7 a;

FIG. 10 a is an front elevation view of an alternative embodiment of thetension link with a link retainer of the present invention;

FIG. 10 b is a side elevation view of the tension link with linkretainer shown in FIG. 8 a;

FIG. 11 is a perspective view of the tension link with head end processof the present invention;

FIG. 12 is a side elevation view of one embodiment of the connector ofthe present invention;

FIG. 13 is a side perspective view of an alternative embodiment of theconnector of the present invention;

FIG. 14 is an bottom perspective view of the connector shown in FIG. 11;

FIG. 15 is a side perspective view of another alternative embodiment ofthe connector of the present invention;

FIG. 16 is a side elevation view of yet another alternative embodimentof the connector of the present invention;

FIG. 17 is a cross-sectional view of one embodiment of the surgicalimplant assembly of the present invention;

FIG. 18 is a perspective view of an alternative embodiment of thesurgical implant assembly of the present invention;

FIG. 19 a is a cross-sectional elevation view of another alternativeembodiment of the surgical implant assembly of the present invention;

FIG. 19 b is a plan view of the surgical implant assembly shown in FIG.17 a;

FIG. 20 is a top plan view of a separate embodiment of a connector;

FIG. 21 is a side cross-sectional view of the connector shown in FIG.20;

FIG. 22 is a side cross-sectional view of a separate embodiment of anattachment device and tension link having truncated portions;

FIG. 23 is a perspective view separate embodiment comprising a tool toinstall the attachment device of the present invention;

FIG. 24 is a cross-sectional view the receptacle end of the tool shownin FIG. 23;

FIG. 25 is a side elevation view of a separate embodiment of an endconnector;

FIG. 26 is a perspective view of the connector shown in FIG. 25;

FIG. 27 is a top elevation view of the connector shown in FIG. 25;

FIG. 28 is a bottom interior perspective view of the connector shown inFIG. 25;

FIG. 29 is a perspective view of the connector shown in FIG. 25 with theconnector shown in combination with an attachment device and a tensionlink;

FIG. 30 is an end cross-sectional view of the combination of structuresshown in FIG. 29;

FIG. 31 is a perspective view of a separate aspect of the inventioncomprising a clamp, wherein the clamp is depicted as a component of astabilization assembly;

FIG. 32 is a perspective view of an upper clamp portion of the clamp;

FIG. 33 is a perspective view of a lower clamp portion of the clamp;

FIG. 34 is a perspective view of the lower and upper portions of theclamp in near interlocking proximity;

FIG. 35 is a cross-sectional view of a clamp having contact ridges;

FIG. 36 is a plan view of a separate embodiment of the clamp, whereinthe clamp is being retrofitted to an existing rod segment;

FIG. 37 is a plan view of yet a separate embodiment of the clamp,wherein the clamp is again being retrofitted to an existing rod segment;

FIG. 38 is a partially exploded perspective view of two stabilizationassemblies including clamps, wherein the assemblies are aligned forimplantation into two vertebra,

FIG. 39 is a side elevation view of one stabilization assembly includinga clamp device after implantation into two vertebra;

FIG. 40 a is a side cross-sectional view of one of the stabilizationassemblies shown in FIG. 38;

FIG. 40 b is a cross-sectional view taken along line 40 b-40 b shown inFIG. 40 a;

FIG. 41 is side elevation view of stabilization assembly having aseparate embodiment of a the clamp device;

FIG. 42 a is side elevation view of a stabilization assembly having yeta separate embodiment of a the clamp device;

FIG. 42 b is a cross-sectional view taken along line 42 b-42 b shown inFIG. 42 a;

FIG. 42 c is a cross-sectional view taken along line 42 c-42 c shown inFIG. 42 a;

FIG. 43 is a plan view of a separate aspect of the invention;

FIG. 44 a is a perspective view of an stabilization assembly havingextended tension link shafts; and

FIG. 44 b is an enlarged detail view of an aspect of an extended tensionlink shaft shown in FIG. 44 a.

While the following disclosure describes the invention in connectionwith those embodiments presented, one should understand that theinvention is not strictly limited to these embodiments. Furthermore, oneshould understand that the drawings are not necessarily to scale, andthat in certain instances, the disclosure may not include details whichare not necessary for an understanding of the present invention, such asconventional details of fabrication.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIG. 1, one embodiment of the attachment device (orconnection device) of the present invention is shown in partialcross-section. The attachment device 10 includes a shank 12 having afirst end 14 and a second end 16. The first end 14 of the shank 12includes a securement mechanism 18. As shown in FIG. 1, the securementmechanism 18 may be screw threads. It is noted, however, that thesecurement mechanism 18 may include any known method of securing oneitem to another. For example, the securement mechanism 18 may be a hook,a plate, a flange, or adhesive. In the case of the securement mechanism18 as a flange or plate, the securement mechanism 18 may requireadditional hardware such as screws, bolts, or adhesive to secure theplate or flange to the intended object. In the case of the securementmechanism 18 as an adhesive, or requiring the additional use ofadhesive, the adhesive would necessarily be applied to the securementmechanism 18, not included within it. Additionally, adhesive could beused with the securement mechanism 18, e.g., applied to screw threads,for additional securement capacity.

The second end 16 of the shank 12 generally comprises an enlarged area20 including a central core 22 and an aperture 24. The second end 16 ofFIG. 1 is shown in cross-sectional view to more clearly show the centralcore 22 and the aperture 24.

With reference to FIG. 2, an embodiment of the second end 16 of theshank 12 is shown. In this embodiment, the enlarged area 20 includes ahollow core 22 and a central aperture 24. The enlarged area alsoincludes an entry channel 26. The entry channel 26 is operativelyconnected with the hollow core 22 such that a tension link 28, having ashaft 30 with a threaded end 32 and a head end 34, may be inserted,threaded end 32 first, through the entry channel 26, the hollow core 22,and central aperture 24 until the head end 34 of the tension link 28 isretained within the hollow core 22 by the central aperture 24.

With reference to FIG. 3, the embodiment of the second end 16 ofattachment device 10 is shown in cross-section. FIG. 3 clarifies theoperational relationship between the entry channel 26, the hollow core22 and the central aperture 24.

With reference to FIG. 4, an alternative embodiment of the attachmentdevice 10 is shown. This embodiment is similar to the embodiment ofFIGS. 2 and 3, but with an additional element. In this embodiment, atension link slot 36 is provided between the entry channel 26 and thecentral aperture 24. The tension link slot 36 allows the shaft 30 of thetension link 28 to be inserted through the tension link slot 36. In thisway, the tension link 28 may be inserted through the tension link slot36 to pass through both central aperture 24 and the entry channel 26.The tension link 28 may then be drawn through the aperture 24 until thetension link head end 34 passes through the entry channel 26 and restsin the hollow core 22. This embodiment may allow the surgeon to insert atension link 28 into an attachment device 10 secured to the human bodyin cases where the obstacles, including the human body itself, or partsthereof, prevent the length of the tension link 28 from extendingcompletely beyond the entry channel 26 opposite the central aperture 24.

FIG. 5 shows an end view, from the second end 16, of the embodiment ofthe attachment device 10 from FIG. 4. FIG. 5 clarifies the relationshipbetween the tension link slot 36 and the central aperture 24, the hollowcore 22 and the entry channel 26. It should be noted that the centralaperture 24 is shown in FIG. 5 as located at top, dead center of theenlarged portion 20 of the attachment device 10. However, the locationof the central aperture 24 may be at any angular relationship to theshank 12. This location of the central aperture 24 applies to this, andevery other, embodiment of the attachment device 10. The hollow core 22should be sized to receive the head end 34 of the tension link 28, inthis and other embodiments of the present invention. Similarly, thecentral aperture 24 should be sized to accommodate the tension linkshaft 30, and with enough clearance to provide the desired angulardisplacement. For example, it may be desirable to provide from about 0to 60 degrees of angular displacement of the tension link 28 from thelongitudinal axis of the attachment device 10. In some instances, asmaller range may be advantageous.

With reference to FIG. 6, an additional alternative embodiment of theenlarged area 20 of the attachment device 10 is shown. In thisembodiment, the enlarged area 20 includes a hollow core 22 and a centralaperture 24, but does not include an entry channel 26. Instead, at leastone expansion slot 38 extends from the central aperture 24 along theexterior surface of the enlarged area 20. The expansion slot 38 extendscompletely through the wall defined by the hollow core 22 and theexterior surface of the enlarged area 20. The embodiment of FIG. 6includes two expansion slots 38 diametrically opposite from one another,however, the number of expansion slots 38 and their location in radialrelation to the central aperture 24 may be selected in the design of theattachment device 10 according to, among other things, the application,or the size and material of construction of the attachment device 10.The expansion slot(s) 38 may allow insertion of the head end 34 of thetension link 28 into the hollow core 22 through the central aperture 24by allowing deformation of the enlarged area 20. As explained in moredetail below, the connector 40, more specifically, the head receptacle42 of the connector 40, when properly installed over the enlarged area20 prevents further deformation of the enlarged area 20, and thus thecentral aperture 24 retains the head 34 of the tension link 28 withinthe hollow core 22.

With reference to FIG. 7, yet another alternative embodiment of theenlarged area 20 of the attachment device 10 is shown. In thisembodiment, at least a portion of the enlarged area 20 includes asubstantially conical portion around the central aperture 24. The headreceptacle 42 of the connector 40 has mating geometry to the enlargedarea 20. Thus, the partially conical shape of the enlarged area 20allows polyaxial positioning of the connector 40 while controllingmovement in one degree of freedom. The connector 40 may rotate aroundthe central axis of the conical section, however, the mating geometry ofthe head receptacle 42 prevents angular displacement relative to thecentral axis of the conical section. Obviously, the central aperture 24may require that the shape of the enlarged area 20 not be truly conical.The central aperture 24 may necessitate the geometry of the enlargedarea 20 to be more aptly described as a truncated cone shape.

FIG. 8 shows the embodiment of the attachment device 10 of FIG. 7 in anelevation view. While FIG. 8 shows the enlarged area 20 to include ahollow core 22, a central aperture 24, and an entry channel 26, it isnoted that conical-shaped enlarged area 20 shown in FIGS. 7 and 8 may beused with any alternative embodiments of the attachment device 10related to the method of insertion of the tension link head 34 into thehollow core 22, including, for example, the expansion slot(s) 38, or thetension link slot 36.

In alternative embodiments not shown in the drawings, the exteriorsurface of the enlarged area 20 may include other configurations. Forexample, the exterior surface of the enlarged area 20 may be formed as apolyhedron, such as a dodecahedron, or be provided with facets. In thisembodiment, the head receptacle 42 of the connector 40 will also have acorresponding geometry. In this way, a polyaxial relationship isprovided between the attachment device 10 and the connector 40, yetlimiting this polyaxial relationship to a finite number of angulardisplacement.

The enlarged area 20 is shown in the drawings as at least approximatelyspheric. It is noted, however that the enlarged area 20 and/or the headreceptacle 42 of the connector 40 may also be aspheric. The use of theaspheric construction of either the enlarged area 20 or the headreceptacle 42, or both, may accommodate the elasticity and deformationof the material the structure. The amount of asphericity may be selectedto control the area of surface contact between the enlarged area 20 andthe head receptacle 42 of the connector 40. The amount of asphericitymay also be selected to control or vary the degree of freedom requiredby the linkage.

Further, in any embodiment or configuration of the enlarged area 20, theexternal surface of the enlarged area 20 may be textured, i.e., providedwith a specified surface roughness. The texture, or surface roughness,of the enlarged area 20 may be selected to properly control the frictionbetween the enlarged area 20 and the head receptacle 42, and thuscontrolling, among other things, the tension force required to securethe devices together or degrees of freedom in their combination. Itshould be noted that the internal wall of the hollow core 22, the headend 34 of the tension link 28, and/or the head receptacle 42 of theconnector 40 may also be provided with a texture, or surface roughness.

With reference to FIGS. 9 a, 9 b, and 9 c, a tension link 28 is shown.The tension link 28 is generally a shaft 30 with a head end 34 and athread end 32. As shown in FIGS. 9 a, 9 b, and 9 c, one embodiment ofthe tension link 28 may include a link retainer 44. The link retainer44, in this embodiment, comprises a projection on the shaft 30 of thetension link 28. The link retainer 44 may be used to prevent unwantedrotation, but not angular orientation, of the tension link 28 within thehollow core 22 of the attachment device 10. An extended tension link 28is shown in FIG. 44, as will be discussed below.

FIG. 9 a shows an embodiment of the tension link with a link retainer 44in partial side elevation. FIG. 9 b shows the same embodiment in frontelevation. FIG. 9 c shows this embodiment in plan view as seen from thethread end 32 of the tension link 28. The thread end 32 of the tensionlink 28 is not shown in FIGS. 9 a, 9 b, and 9 c.

With reference to FIGS. 10 a and 10 b, an alternative embodiment of thelink retainer 44 of the tension link 28 is shown. The tension link 28 isshown in partial side elevation and partial front elevation, in FIG. 10a and FIG. 10 b, respectively. Again, this view is “partial” because thethread end 32 of the tension link 28 is omitted from the drawing. Thelink retainer 44 in this embodiment is a projection that spans theintersection of the shaft 30 and the head end 34 of the tension link 28and extends partially along the surface of the head end 34. Thisembodiment may be used in conjunction with the embodiment of theattachment device 10 including the tension link slot 36, as shown inFIGS. 4 and 5 above. As in the previous embodiment, the tension link maybe prevented from unwanted rotation of the tension link 28 within thehollow core 22. The link retainer 44 may be placed in contact with thewall of the tension link slot 36 to prevent such rotation.

With reference to FIG. 11, an alternative embodiment of the tension link28 is shown. The tension link 28 again includes a shaft 30 with a headend 34 and a thread end 32, and, in this embodiment, a head end process46. The head end process 46 is a projection on the head end 34 of thetension link 28. The head end process 46 may be used to prevent rotationof the tension link 28 within the hollow core 22 similar to the linkretainer 44. However, this embodiment would most commonly be used withan attachment device 10 having a entry channel 26, and the head endprocess 46 could be placed in contact with a wall of the entry channel26 to prevent the rotation.

With reference to FIG. 12, an embodiment of the connector 40 is shown.The connector has a receiving end 48 and a rod end 50. The receiving end48 includes a head receptacle 42 for receiving the enlarged area 20 ofthe attachment device 10. The rod end 50 includes a rod aperture 52 forreceiving a implant component 54, such as a spinal rod implant or otherdevice. A tension link cavity 56 is provided from the head receptacle 42to the rod end 50. The tension link cavity 56 is sized to allow theinsertion of the thread end 32 of a tension link 28 through theconnector 40. In the embodiment of the connector 40 shown in FIG. 12, alink nut recess 58 is provided at the rod end 50 adjacent to the tensionlink cavity 56 for seating a link nut 60 used to secure the connector 40to the tension link 28. As shown in FIG. 12, the connector may include agap 62 located medially between the receiving end 48 and the rod end 50,and in operative relationship with the rod aperture 52 such that whenthe gap 62 is closed, the rod aperture 52 may secure the implantcomponent 54. In this embodiment, tightening of the link nut 60 on thetension link 28 closes the gap 62, and thus secures the implantcomponent 54, concurrently with securing the connector 40 to theattachment device 10 in a desired position. The embodiment shown in FIG.12 includes the alternative feature of a link retainer recess 64. Thelink retainer recess 64 is a void located along the tension link cavity56 and adjacent to the head receptacle 42. The link retainer recess 64accommodates the link retainer 44 of the embodiment shown in FIGS. 9 a,9 b and 9 c, such that the link retainer 44 may contact the wall of thelink retainer recess 64 and prevent undesired rotation of the tensionlink 28. The link retainer recess 64 should be sized accordingly.

Referring now to FIG. 13, an alternative embodiment of the connector 40of the present invention is shown. Like the embodiment of FIG. 13, theconnector 40 of this embodiment has a receiving end 48 with a headreceptacle 42, a rod end 50 with a rod aperture 52, and a tension linkcavity 56. In this embodiment, however, the rod aperture 52 is offsetfrom the body of the connector 40. The ability to offset the rodaperture 52 may provide greater latitude to the surgeon when attemptingto avoid obstacles such as bones or other tissues.

FIG. 14 shows the embodiment of the connector 40 of FIG. 13 from thereceiving end 48. The tension link cavity 56 in this embodiment does notinclude the alternative element of the link retainer recess 64.

With reference to FIG. 15, an alternative embodiment of the connector 40is shown. In this embodiment, the implant component 54 is secured in therod aperture 52 separately from securing the connector 40 to theattachment device 10 by the tension link 28. The tension link cavity 56does not intersect the gap 62 in the wall of the rod aperture 52.Instead, a portion of the wall of the rod aperture forms a tab 66 with aimplant securement hole 67. The tab 66 may be secured to the connector40 by an implant securement screw 69 inserted through the implantsecurement hole 67 and into the connector 40. This configuration mayprovide further offset capacity for the connector from the attachmentdevice 10.

Referring now to FIG. 16, a further embodiment of the connector 40 isprovided wherein the implant component 54 is secured in the rod aperture52 separately from securing the connector 40 to the attachment device10. As in the embodiment of FIG. 15, a portion of the wall of the rodaperture forms a tab 66 with a implant securement hole 67. The tab 66may be secured to the connector 40 by an implant securement screw 69inserted through the implant securement hole 67 and into the connector40. However, in this embodiment, the tab 66 is located toward theexterior of the connector 40.

With reference to FIG. 17, a possible combination of the above describedelements is provided to show a surgical implantation system. Thesurgical implant system 70 includes an attachment device 10, a tensionlink 28, a connector 40, and a link nut 60. The implant component 54 isomitted from this drawing. The tension link head end 34 is inserted intothe hollow core 22 of the attachment device 10. The tension link 28extends through the tension link cavity 56 of the connector 40 such thatthe enlarged area 20 of the attachment device 10 is received into thehead receptacle 42 of the connector 40. The connector 40 may then besecured to the attachment device 10 in proper position by tightening thelink nut 60 on the tension link 28. In this embodiment, tightening thelink nut 60 will also close the rod aperture gap 62 and secure theimplant component 54 within the rod aperture 52.

As an aside, the head receptacle wall 68 is shown extending toapproximately the “equator” or diameter of the enlarged area 20 of theattachment device 10. It should be noted that the extent that the headreceptacle wall 68 engages the enlarged area 20 may be varied. Forinstance, a smaller wall 68 engagement may be desirable to increase thepolyaxial adjustment of the assembly. Alternatively, it may be desirableto provide greater wall 68 engagement with the enlarged area 20 toprevent unnecessary deformation of the enlarged area 20, for examplewhen the enlarged area 20 is provided with an expansion slot 38 or atension link slot 36. Further, if the head receptacle wall 68 isdesigned for engagement beyond the “equator” of the enlarged area, thehead receptacle wall 68 may match the contour of the enlarged area 20.In other words, the size of the head receptacle 42, at the farthestpoint on the receiving end 48 of the connector 40, may be smaller thanthe maximum size of the enlarged area 20 at its “equator.” This mayprovide an additional advantage to the surgeon. In this situation, atactile or audible signal may be provided when the enlarged area 20 isproperly received into the head receptacle 42.

With reference to FIG. 18, an alternative arrangement of the surgicalimplant system 70 is shown. In this embodiment, the connectors 40 securea implant component 54, in this case a rod, to the attachment devices10. The orientation of the attachment devices 10 illustrate thepolyaxial nature of the system 70. The attachment devices may be securedto whatever structure is necessary at different angles and on differentplanes.

Referring now to FIGS. 19 a and 19 b, an alternative embodiment of thesurgical implantation system 70 is provided. In this embodiment, adynamic system is created wherein the implant component 54 is allowed tomove freely along its longitudinal axis within connector rod aperture52. This is accomplished by manufacturing some clearance tolerancewithin the rod aperture 52 when the link nut 60 is completely tightenedon tension link 28. FIG. 19 a also shows an alternative embodiment of aretaining recess 72 adjacent to the connector rod aperture 52. Theretaining recess 72 corresponds with a retaining process 74 on theimplant component 54 to limit the extent of dynamic nature within theimplant. The retaining recess 72 and the retaining process 74 are sizedand work in relation to one another such that the longitudinal movementof the implant component 54 is arrested when the retaining process 74nests in the retaining recess 72.

Although it is not shown in the drawings, it is also possible to use theretaining process 74 without the retaining recess 72. It this aspect,the longitudinal movement of the implant component 54 is arrested whenthe retaining process 74 contacts the exterior surface of the connector40 at the rod aperture 52. It is also possible to use either of the twoabove embodiments on either side of the rod aperture 52, wherein thelongitudinal movement of the implant component 54 can be constrained inone or both directions.

Additional embodiments of the present invention are not shown in thedrawings. For example, it is expected that the attachment device 10 maybe used in conjunction with a hook in place of the tension link 28. Inthis embodiment, the hook would have a ball end and a hook end. The ballend would be inserted into the central core 22 of the attachment device10 and the hook end would be used to secure some bodily structure, suchas a bone. The hook rod would be capable of polyaxial movement.

The present invention also relates to a method of using the embodimentsas set forth above. In one embodiment, the method using a surgicalimplant system 70 would first require the selective insertion of theattachment device 10 into a human bone. The tension link head end 34could then inserted into the hollow core 22 of the attachment device 10.The step of insertion of the head end 34 would depend upon theembodiment of the attachment device 10 selected. For example, if anattachment device 10 with an entry channel 26, but no tension link slot36, is provided, the tension link 28 is positioned in the aperture 24 byway of the entry channel 26. The connector 40 is positioned on thetension link 28 by inserting the tension link 28 through the connectortension link cavity 56.

At this point, the surgeon can position the connector 40 such that theimplant component 54, when properly inserted in connector rod aperture52, is held in the desired position along the spinal column. The surgeoncan then secure the position of the implant component 54 and theconnector 40 in relation to the attachment device 10 by tightening thelink nut 60 on the tension link threaded end 32. This process isrepeated, as necessary, along the spinal column at various points alongthe implant component 54. In this way, the surgeon has implemented theabove described embodiments as a method for using the surgical implantsystem, for example, in repairing a degenerative spinal condition.

It is understood that the present invention has application outside thesurgical implantation field. The polyaxial securing mechanism of thepresent invention is not limited to medical implants. The presentinvention, for example, could be used to secure guy wires or rods. Inthis application, the anchor screw could be inserted into the ground,e.g., set directly in to the soil, mounted in a concrete footing, orsimilar mounting. The guy wire or rod (i.e., the tension link) couldthen be inserted through the anchor screw and connected to the structureto be secured. The guy rod may include a turnbuckle. The turn buckle canthen be adjusted to the desired tension in the guy rod. In this way,some room for error in the location of the anchor bolt is built into theinstallation process. The guy rod may be installed between the anchorscrew and the structure without placing undue stress on the guy rod, orrequiring unnecessary bending of the guy rod, due to misalignmentbetween the connection point on the structure and the anchor boltposition. This is especially beneficial when a turnbuckle is implementedin the guy rod. The polyaxial nature of the anchor screw would allow theturnbuckle to be more easily adjusted since the stress within the guyrod is limited to the axial direction of the rod, i.e., no bendingstress on the turnbuckle.

This is just one example of the possible applications of the presentinvention outside the field of medical implants. Other applications, byno means exhaustive, may include connecting legs of a tripod to a baseand mounting track lighting fixtures.

Referring now to FIGS. 20 and 21, a further aspect of the presentinvention is to provide a multi-piece connector 80. The advantage of amulti-piece connector 80 is its ability to offer differentconfigurations for attachment of a rod 54 to bone screws or attachmentdevices 10 when geometry requirements of the implant area so dictate.

FIG. 20 is a top view of one possible configuration of an assembledmulti-piece connector 80. FIG. 21 illustrates a side cross-sectionalview of the same multi-piece connector 80. The multi-piece connector 80includes a first anchor section 82 and a second hook section 84. Thefirst anchor section 82 is positioned proximate the bone screw orattachment device 10. The second hook section 84 is positioned proximatethe implant component or rod 54, such that it “hooks” around rod 54 andsecures it against a cam 86 that is an integral part of first anchorsection 82. After assembly of the multi-piece connector 80, a tensionlink 28 is used to secure the various components of the system togetherby tightening a tension link nut 60 at the distal end of the tensionlink 28. As may be appreciated, the aforementioned and describedmulti-piece connector 80 is illustrated as having two pieces, however,multi-piece connectors 80 with more than two pieces is possible andappropriate for a potential application or patient's needs.

Referring now to FIG. 22, in yet a further aspect of the invention, forattachment devices 10 having an entry channel 26 and an tension linkslot 36, a truncated area 90 is incorporated into the entry channel 26of the attachment device 10. In a corresponding manner, the head end 34of tension link 28 possesses a corresponding flat or truncated area 92that may be aligned with the truncated area 90. The attachment device 10and tension link 28 are thereby mated for implanting such that they areconfigured in a manner that requires specific manipulation to enter andrelease the tension link 28 from the attachment device 10. These matingfeatures allow the tension link 28 to be installed at the same time thatthe attachment device 10 is secured to the vertebra, with minimal chancethat the tension link 28 will become uncoupled from the attachmentdevice 10 prior to tightening using a tension nut because the tensionlink 28 has to be tipped to properly align the truncated areas 90 and 92to release. However, this configuration allows the surgeon to remove thetension link 28 from the attachment device 10, if the surgeon so desiresat some point during implantation. In this case, the surgeon wouldmanipulate the tension link 28 to a proper angles such that it releasesfrom the attachment device 10.

Referring now to FIGS. 23 and 24, in a further embodiment of theinvention, a tool 94 is provided to install the attachment device 10.The tool 94 possesses morphological or structural features thatcorrespond to the shape of the attachment device 10 in such a way thatthe tool is used to provide both a downward force and a rotational forceor torque to the attachment device 10, and thereby provide a means ofimplanting the attachment device 10 into the patient's bone. Therefore,the tool 94 possesses a tool receptacle end 95 that mates with thefeatures of the enlarged area 20 of the attachment device 10.Specifically, the tool 94 preferably possesses a tool receptacle 96 thatsurrounds the outer and upper portion of enlarged area 20 of attachmentdevice 10. More preferably, the tool 94 possesses a structure that mateswith the hollow core 22 of the attachment device. More preferably yet,the tool 94 possesses a projection 97 that at least partially fitswithin the entry channel 26 of attachment device 10, and thereby allowsthe surgeon or installer to provide torque to the attachment device 10by turning the tool, thereby providing force to screw the attachmentdevice 10 into bone. Alternately, as shown in FIG. 24, the toolpossesses a projection that at least partially fits into the tensionlink slot 36 of attachment device 10, and thereby allows the surgeon orinstaller to provide torque to the attachment device 10 to screw theattachment device 10 into bone. The tool 94 may also include a handle 99or some other means that allows the tool 94 to be rotated by thesurgeon. In summary, the tool 94 possesses a tool receptacle 96 thatincludes one or multiple projections 97 that at least partially fit intoeither the hollow core 22, the tension link slot 36, the entry channel26, the expansion slot(s) 38, or any combination thereof, to allow thesurgeon a means of providing torque to screw the attachment device 10into bone.

Still referring to FIG. 24, in a different aspect of the toolembodiment, the tool 94 is used to install both the attachment device 10and the tension link 28 at the same time. In use, the tension link 28 isfitted into the attachment device 10. Subsequently, the attachmentdevice 10 and tension link 28 are simultaneously installed. Accordingly,the tool 94 preferably possesses a hollow interior shaft 98 thatreceivingly accepts the tension link shaft 30 of tension link 28. Thetool receptacle 96 preferably fits over the upper and outer surface areaof the enlarged area 20 of attachment device 10, with tension 28 inplace. The receptacle 96 optionally includes a nylon, teflon or othertype of insert to temporarily restrain the screw while the surgeonlocates the location for insertion.

The tool 94 either possesses a projection 97 to at least partially fitinto a structure of the attachment device 10, such as a tension linkslot 36, or alternately, the tool 94 interacts with the enlarged area 20of attachment device 10 utilizing a lathe-chuck-type of frictionalfitting (not shown). The lathe-chuck-type of frictional fitting graspsthe enlarged head area 20 of attachment device 10 and allows the surgeonmeans to provide torque to the attachment device 10 to screw theattachment device 10 into bone. Alternately, the enlarged head area 20of attachment device 10 possesses facets (not shown) that allow a matingtool receptacle 96 to be placed over or around the enlarged head area 20to thereby permit torque to be applied to the attachment device 10. Inyet an alternate embodiment, a nut-like multi-faceted structure (notshown) that is an integral part of attachment device 10, and existingpreferably below the enlarged area 20 and preferably at the upperregions of shank 12 is used to provide a means of grasping attachmentdevice 10 with a tool capable of providing a torque force to attachmentdevice 10 to screw attachment device 10 into bone.

Referring now to FIGS. 25-30, in a further embodiment of the presentinvention, an end connector 40′ is incorporated directly into the rod 54in the form of a receptacle 100. When placed at the end of a rod 54, theprincipal advantage of the end connector 40′ feature is to shrink theprofile of the attachment device 10, connector 40′, and rod 54configuration as a system, and thereby reduce the length of rod 54 thatis longitudinally exposed beyond the attachment device 10 or screwlocation. In so doing, in spinal implant applications the next vertebrabeyond the end of the rod is not exposed to potentially impacting therod section that would have previously extended longitudinally beyondthe connector location. This can reduce patient pain and increasepatient mobility. A further advantage is that the smaller profileresults in less tissue displacement in the vicinity of end connector40′.

Still referring to FIGS. 25-30, end connector 40′ is shown located atthe end of a rod 54; however, it is to be understood that the endconnector 40′ could be located within any portion of an implant. In apreferred embodiment, the end connector 40′ includes a receptacle 100that is in the form of a socket that preferably includes a socketexterior 102 and a socket interior 104. The socket interior 104essentially acts as a low-profile connector. The socket interior 104 maybe any shape that is configured to correspondingly accept an attachmentdevice 10. Thus, the receptacle 100 is sized to fit over and receivinglyaccept the enlarged area 20 of the attachment device 10. Accordingly,socket interior 104 is preferably a recessed area at the end of a rod 54that fits over the enlarged area 20 of the attachment device 10. Asshown in FIG. 29, the socket interior 104 is preferably nearlysemi-spherical, to match a spherical-type shape of enlarged area 20 ofattachment device 10. However, socket interior 104 may be a vast varietyof shapes that match the enlarged area 20 of the attachment device 10.Such shapes include rectangular cube, cubic, pyramid, ellipsoid,multi-faceted, conical, cylindrical, tetrahedral, elongated,combinations of these shapes, truncated portions of these shapes, or anyother shape that may receivingly accept the enlarged area 20 of anattachment device 10. Within the center of the receptacle 100 is atension link cavity 56 that is sized to accept the shaft 30 of thetension link 28. Referring to FIGS. 26-28, tension link cavity 56 can beseen as an opening through the top of receptacle 100.

FIGS. 29 and 30 show different views of attachment device 10, tensionlink 28, tension link nut 60, and receptacle 100. Installation of a rod54 possessing the receptacle 100 would include installation of theattachment device 10, preferably by interconnecting the securementmechanism 18 of attachment device 10 to a target location on one of thepatient's spinal vertebra or other bone segment. Subsequently, thetension link 28 is installed by feeding the shaft 30 of tension link 28through the entry channel 26 of the attachment device 10, such that theshaft 30 of the tension link 28 is pulled through the central aperture24 of the attachment device 10, thereby positioning the head end 34 ofthe tension link 28 within the hollow core 22 of the attachment device10. Alternately, tension link 28 may be fitted into attachment device 10prior to installation of the attachment device 10, or an attachmentdevice having an expansion slot 38 may be used, whereby an entry channel26 is not used to place the tension link head 34 into the hollow core 22of the attachment device. In yet another alternative, the tension link28 may be permanently mounted into attachment device 10 duringmanufacture, such that both the attachment device 10 and the tensionlink 28 form one piece of hardware, with the head end 34 of tension link28 permanently mounted, but still rotatable, within the hollow core 22of attachment device 10.

Following installation of the attachment device 10 with the tension link28 in place, receptacle 100 of rod 54 is then placed over the attachmentdevice 10 by feeding the tension link 28 through the tension link cavity56 within the receptacle 100. The rod 54 is then secured to theattachment device 10 by advancing a tension link nut 60 on to thetension link 28.

The outside diameter of the receptacle 100 may vary depending upon theapplication; however, a diameter of about 10 mm is typical forreceptacles 100 used in spine related surgery. The receptacle wall 105,defined as the area between the socket exterior 102 and socket interior104, will preferably have a thickness necessary to provide sufficientstructural confinement of attachment device 10 after tension link 28 isinstalled and link nut 60 is tightened on to shaft 30 of tension link28. The thickness of the receptacle wall 105 will, therefore, dependupon the types of material used to make the various components, such asthe receptacle 100, attachment device 10 and tension link 28.

In a separate embodiment, a receptacle 100 is positioned at each end(not shown) of a rod 54. In this manner, the rod 54 is used to span thedistance between at least two attachment devices 10. Therefore, a seriesof various lengths of rods may be produced that permit the surgeon orinstaller to choose the correct length for any given installation.Alternately, a custom made rod may be produced to match the needs of thegiven installation requirements. Preferably, a rod 54 that is used tospan a single vertebral joint is between 10 to 60 mm in length. However,lengths are determined on a case-by-case basis depending upon thepatient's needs or the alternate application. For example, should theinvention described herein be used in veterinary medicine, obviously thedimensions of the components will vary depending upon the size and typeof animal undergoing treatment.

In a separate embodiment of the invention, one or more receptacles arelocated within the interior length of a rod. When receptacles are usedat an interior rod location (not shown), the advantage to the patient isless tissue displacement. Here, individual receptacle locations may beproduced within a length of rod, thereby reducing the need for use of aseparate connector at each location along the length of the rod.

In still a separate embodiment, a continuous channel socket (not shown)is produced along the length of the underside of a rod. In thisembodiment, individual tension link cavities may be drilled at thedesired location just prior to implanting the rod. Alternately, the rodof this embodiment may be manufactured with a continuous tension linkcavity (not shown) that possesses means for maintaining the position ofa tension link and thereby prevents movement of the tension link alongthe longitudinal length of the rod. These means preferably include aseries of shapes that maintain the position of the shaft of the tensionlink after the shaft it is fed through an individual tension link cavityof the continuous tension link cavity. The exterior surface of theenlarged area of attachment device may include detents or depressionsthat receivingly accept spring loaded balls or surficial features suchas ridge texturing that is interconnected to the underside of continuouschannel socket. Alternately, the surface features are preferably locatedon the exterior surface of the enlarged area of the attachment device,thereby interlocking with indentations located on the underside ofcontinuous channel socket. Surficial features may include texturing,ridges, bumps, projections, protrusions, indentations, adhesives, andcoverings or coatings of alternate materials.

A further inventive aspect comprises a clamp device. Among its manypotential uses, the clamp feature is used to attach a new section of rodto an existing section of rod, to extend a section of rod, to providelength adjustability to a rod, to provide a means of attaching aseparate structure to the end of a new or existing rod, to provide ameans of attaching a separate structure to the end of a new or existingrod while adjusting the length of the rod, or to reinforce an existingsection of rod. In general, the purpose of clamp is to allow the lengthof the rod to be adjusted at the surgical site without having to cut therod, or custom order a length of rod, or use a standardized rod lengththat may not fit the patient.

Referring now to FIG. 31, a perspective view of one embodiment of thestabilizing assembly of the present invention is shown. The assemblyincludes a section of rod, or rod member, that is grasped by adjustableclamp 200. The clamp 200 is preferably comprised of two pieces that workto clamp the rod member, thereby forming a rod assembly that may beadjusted at the surgical site to accommodate different lengthrequirements.

Referring now to FIGS. 31-34 the first piece in the assembly is theinterior rod section or first rod member 202; the second piece is thelower clamp portion 204; and the third piece is the upper clamp portion206. As shown in FIG. 33, lower clamp portion 204 includes a clampregion 208. Similarly, as shown in FIG. 32, upper clamp portion 206includes a clamp region 210. The clamp regions 208 and 210 serve as aninterlocking zone or compression zone. The lower clamp portion 204 andthe upper clamp portion 206 interlock as shown in FIG. 34. During theinterlocking of lower clamp portion 204 with upper clamp portion 206,the two pieces are brought together as shown in FIG. 34. The bringingtogether of the lower clamp portion 204 and the upper clamp portion 206forces the two clamp regions 208 and 210 together. As shown in FIG. 31,upon complete assembly, such as after a surgical procedure, clampregions 208 and 210 preferably substantially encircle or telescopearound a portion of interior rod member 202. Accordingly, upon completeassembly, a portion of interior rod member 202 is preferably situated tothe interior of lower clamp portion 204 and upper clamp portion 206 andis held in an interlocked configuration by the compressive forces actingin the clamp regions 208 and 210 of the lower and upper clamp portions204 and 206.

Interior rod member 202 and clamp regions 208 and 210 may possesssurface features that interlock and aid in securing the interior rodmember 202 to the clamp regions 208 and 210. For example, clamp regions208 and 210 may include detents or depressions that receivingly acceptspring loaded balls or surficial features such as ridge texturing thatis interconnected to the exterior surface of interior rod member 202.Surficial features may include texturing, ridges, bumps, projections,protrusions, indentations, adhesives, and coverings or coatings ofalternate materials. For example, FIG. 35 illustrates a series of fourridges 209 that are used to concentrate pressure from the lower clampportion 204 and upper clamp portion 206 to the interior rod member 202.Furthermore, although not required, openings through the lower clampportion 204 and the upper clamp portion 206 may be used to receivesecuring devices such as pins, screws, bolts, hooks or anchors thatinterconnect the interior rod member 202 with the lower clamp portion204 and/or the upper clamp portion 206. For example, although notrequired, at least one set screw may be used to interlock the interiorrod member to one of the lower or upper clamp portions 204, 206. FIG. 31illustrates the use of an optional set screw 211 to further interlockthe interior rod member 202 with the upper clamp portion 206. Thescrew(s) can be oriented in a variety of directions to achieve thisgoal. Metal or resilient bands (not shown) may also be used to wrap andsecure the interior rod member 202 with the lower clamp portion 204and/or the upper clamp portion 206.

As shown in FIGS. 32-34, the lower clamp portion 204 includes a securingend 212, and upper clamp portion 206 includes a securing end 214.Securing ends 212 and 214 are used to secure the lower clamp portion 204and the upper clamp portion 206 to the attachment device 10, such as byusing a tension link 28. Accordingly, securing ends 212 and 214 arepreferably sized to receive the enlarged area 20 of the attachmentdevice 10. More particularly, the securing ends 212 and 214 preferablyinclude receptacles 100 that receive the enlarged area 20 of theattachment devices 10. Preferably, the securing ends 212 and 214 includea socket-like shaped portion that fits over the enlarged area 20 of theattachment device 10. More preferably, securing end 212 fittinglycooperates with securing end 214. Although not required, securing end212 and securing end 214, may also include surficial features (notshown) such as texturing, ridges, bumps, projections, protrusions, orindentations that cooperate with one another to prevent rotation ormovement of the securing ends relative to one another once assembled.

Preferably, a tension link cavity 56 passes through securing ends 212and 214, and provides for insertion of the shaft 30 portion of tensionlink 28 through securing ends 212 and 214. Link nut 60 may be used tosecure the lower clamp portion 204 and the upper clamp portion 206 tothe tension link 28, and therefore to the attachment device 10.Furthermore, by tightening the link nut 60 that is threaded onto thetension link 28, the lower clamp portion 204 and the upper clamp portion206 are brought together in tight cooperation. This action tightensclamp region 208 and clamp region 210 around interior rod member 202,thereby securing interior rod member 202 from movement longitudinallyrelative to lower clamp portion 204 and upper clamp portion 206.Accordingly, clamp 200 shares similarities to a pliers-type tool byutilizing a compression force at the securing ends 212 and 214 of thelower clamp portion 204 and the upper clamp portion 206 to create acompression force around the interior rod member 202 at the clampregions 208 and 210. The interlocking feature of the clamp 200 sharessimilarities to a pair of pliers because the compression force exertedat one end, the securing ends 212 and 214, is translated to compressionforces at the interlocking zone, or compression zone, or clamp regions208, 210. In addition, the installation of the clamp 200 sharessimilarities to forceps used in obstetrics during the delivery of ababy, whereby the device is assembled in pieces to provide a means ofgrasping the intended object. In the case of the present invention,however, means are employed to secure the grasping function or clampregions 208 and 210 of the clamp 200 by tightening the securing ends 212and 214 of the lower clamp portion 204 and upper clamp portion 206.

Lower clamp portion 204 and the upper clamp portion 206 are preferablyof a shape that is approximately a half-cylinder. More preferably, asshown in FIGS. 32-34, the half-cylinder shapes include bends in theclamp regions 208 and 210. In this aspect, the lower clamp portion 204bends within clamp region 208 to encompass the upper region of interiorrod member 202 after the assembly is complete. Similarly, the upperclamp portion 206 bends within clamp region 210 to encompass the lowerregion of interior rod member 202 after the assembly is complete. Morespecifically, in a preferred embodiment, the lower clamp portion 204includes a first bend 218 at the lower side of interior rod member 202,and a second bend 220 at the upper side of interior rod member 202. In asimilar but mirrored fashion, upper clamp portion 206 includes a firstbend 222 at the upper side of interior rod member 202, and a second bend224 at the lower side of interior rod member 202.

Between the first bend 218 and the second bend 220 of the lower clampportion 204, the lower clamp portion 204 includes an opening 219 whereininterior rod member 202 is slidably received when the interior rodmember 202, lower clamp portion 204, and upper clamp portion 206 areassembled. Similarly, between the first bend 222 and the second bend 224of the upper clamp portion 206, the upper clamp portion 206 includes anopening 223 wherein interior rod member 202 is slidably received whenthe interior rod member 202, lower clamp portion 204, and upper clampportion 206 are assembled.

Among a number of favorable characteristics, the clamp 200 essentiallyallows the length of the structural member (typically a rod) spanningtwo bone screws or attachment devices 10 to be adjusted at the surgicalsite without having to cut the rod because the length of the rod isadjustable by moving the interior rod member 202 within the lower clampportion 204 and the upper clamp portion 206 prior to fixing securingends 212 and 214 by securing an interconnecting mechanism, such as bytightening a link nut 60. This eliminates the need for having to customorder a length of rod, or otherwise use a standardized rod length thatmay not fit the patient, and thereby cause decreased performance andpotentially increased pain to the patient. Furthermore, utilizing thecomponents of the present invention, the entire assembly can betightened by securing a link nut 60 at each attachment device 10 afterthe interior rod member 202 is placed within the lower clamp portion 204and the upper clamp portion 206. This greatly simplifies the surgeon'sefforts and serves to reduce operation time and associated patient risk.

In addition to the above noted characteristics inherent to using a rodimplant with the clamp 200 feature, the clamp 200 is also especiallyapplicable to adding an additional length of rod 54, or providing lengthadjustability to a rod being implanted concurrently with theimplantation of the clamp 200 device, or can be used to add additionallength to an already existing portion of rod that had previously beenimplanted into the patient during a prior surgical procedure. A methodfor subsequently retro-fitting a portion of rod possessing the clamp 200to an existing portion of rod is now presented.

Where an existing rod implant exists, the patient's surgical site wouldbe partially exposed at the end of the existing rod requiring extension.If a sufficient length of rod or rod run-out length exists beyond anexisting rod connector that attaches the existing rod to the bone, thenthe clamp 200 may be interconnected directly to the rod run-out lengthwith additional length of new rod implanted as the patient's conditionsmay warrant. Alternately, if sufficient rod run-out length does notexist, as shown in FIG. 36, then the first existing connector can beremoved, thereby exposing a sufficient length of rod for the clamp 200to clamp the existing rod. More than one connector may have to beremoved in certain cases.

A further option comprises clamping the clamp 200 over a sufficientlength of rod that may be accessible between existing connectors. Here,the clamp 200 would preferably include at least one additional bend asshown in FIG. 37. Alternately, two additional bends may be used in orderto align the clamp portions of the clamp 200 between the existingconnectors. This option then eliminates the necessity for removing atleast the first existing connector. The advantage of the above listedmethods for attaching the clamp 200 invention to an existing rod is thatthe existing rod does not have to be completely exposed and removed,with a new longer rod implanted. Therefore, a smaller incision isnecessary and consequently, multiple benefits are realized includingdecreased medical costs and less pain to the patient. Another advantageis that a second parallel rod does not need to be installed adjacent thefirst existing rod. Accordingly, structural support can be achieved inthe form of an extension using clamp 200 and adapting the lower clampportion 204 and the upper clamp portion 206 to accept the existing rod.

Referring now to FIGS. 38-40 a-b, in a separate embodiment, an assemblyis provided that utilizes the various components listed above. Thus, oneapplication of this embodiment then is the installation of two separateattachment devices 10 that are then fitted with the other devices. Inuse, attachment devices 10 are installed first. In one preferred methodof use, the attachment devices 10 are pedicle screws that are installedinto two vertebra, a first vertebra V₁ and a second vertebra V₂. Morepreferably, as shown in FIG. 38, right and left assemblies are installedon either side of the spinous process. Installation of the attachmentdevices 10 is followed by the installation of tension links 28 throughor into the two attachment devices 10. Alternately, the tension links 28may be placed into the attachment devices 10 prior to installing theattachment devices 10 into their intended positions. Subsequent toinstalling the attachment devices 10 with the tension links 28 in place,an interior rod member 202 having a receptacle 100 and a rod member 54is implanted over one of the attachment devices 10 and secured with afirst link nut 60. Installation of interior rod member 202 is preferablyperformed in conjunction with installing a lower clamp portion 204 andan upper clamp portion 206 over the remaining attachment device 10 whileclamping the clamp regions 208 and 210 of the lower clamp portion 204and an upper clamp portion 206, respectively, around the interior rodmember 202. Subsequently, securing ends 212 and 214 are securedlyattached to the second attachment device 10 by placing a second link nut60 onto the exposed portion of the tension link 28 of the secondattachment device 10. Of course, the clamp regions 208 and 210 may beadjusted during tightening securing ends 212 and 214 using second linknut 60 to ensure an appropriately configured arrangement of interior rodmember 202, clamp 200, attachment devices 10, and tension links 28. Theresulting assembly spans disk D. Accordingly, the interior rod member202 serves as a first rod member, and the lower clamp portion 204 and anupper clamp portion 206 serve as a second rod member that combine tostructurally bridge disk D when interconnected to attachment devices 10by interconnecting mechanisms, such as tension links 28.

Referring now to FIG. 41, a separate embodiment of the clamp 200′ isprovided wherein the clamp 200′ includes a lower clamp portion 204′ andan upper clamp portion 206′. This embodiment provides a differentconfiguration for the clamp. However, similar to the clamp 200 describedabove, the compressive forces are applied by the clamp regions 208′ and210′ by tightening the securing ends 212′ and 214′ using aninterconnection mechanism, which preferably is a link nut 60 applied toa tension link 28. As shown in FIG. 41, ridges 209 may be used withinthe interior of lower clamp portion 204′ and an upper clamp portion206′. As shown in FIG. 41, three ridges 209 are used, thereby wedginginterior rod member 202 between the lower clamp portion 204′ and anupper clamp portion 206′ when link nut 60 is tightened. Thus, it is tobe understood that the present invention encompasses various embodimentswhereby an interlocking force can be applied to a clamp region of astructure that is at a spaced distance S away from the securing ends.

Referring now to FIG. 42 a-c, a further illustrative example of analternate embodiment of the clamp is shown. Clamp 200″ includes a lowerclamp portion 204″ and an upper clamp portion 206″. Lower clamp portion204″ includes a hollow interior 242 for receiving interior rod member202. The hollow interior 242 also includes an upper space 244 forreceiving upper clamp portion 206″. Upper clamp portion 206″ is a memberthat includes a heal projection 246 and a toe projection 248. Upontightening the securing end 214″ of upper clamp portion 206″, the healprojection 246 presses down on interior rod member 202 while the toeprojection 248 presses up on an upper interior surface 250 of lowerclamp portion 204″. Upper clamp portion 206″ may be biased to increasethe forces applied to its heal projection 246 and toe projection 248when it is tightened into place. The resulting forces compress andinterlock the interior rod member 202 against the lower interior surface252 of lower clamp portion 204″, thereby securedly holding interior rodmember 202 within the lower clamp portion 204″ and upper clamp portion206″. As shown in FIG. 42 a, two ridges 209 are preferably providedalong the lower interior surface 252 of lower clamp member 204″. The tworidges 209 are spaced apart such that heal projection 246 of upper clampportion 204″ is positioned intermediate the two ridges, therebyproviding a triangulated force pattern on interior rod member 202.

Referring now to FIG. 43, a separate embodiment comprising a telescopingrod 230 is shown. The telescoping rod 230 preferably has a receptacle100 placed at each end of the telescoping rod 230. An inner first rodportion 232 slidably receives a second outer rod portion 234, therebyallowing adjustment of the length of the rod prior to securing thereceptacles over previously installed attachment devices 10 withcorresponding tension links 28. The telescoping rod may be configuredsuch that one portion fits within another portion, as shown, or oneportion of the rod may be positioned above or below the other portion.The telescoping portions may interlock without the use of additionalcomponents by, for example: means of a friction fit between thetelescoping portions; locking collars; pins; etc. One aspect of apreferred embodiment bares similarities to a Chinese finger trap toy,whereby movement is allowed in one direction, but resisted in the otherdirection. Alternately, the sections of the telescoping rod may threadinto one another, thereby providing both a length adjustment feature anda locking feature. Alternately yet, the telescoping portion of the rodmay optionally be secured using securing means such as a bolt, setscrews 211 (as shown in FIG. 43), band, or other similar device, ormultiple such devices. In yet another alternative, a shim of variouspossible shapes including tapered regions may be pushed into orotherwise placed along a portion of the length of the telescoping rodsegments in order to lock the segments together. In yet anotheralternative, the rod may be adjusted to its final intended length andsecured using adhesives or an epoxy such as methyl metacrylate. Theadhesives or epoxy may be applied to the surface of portions of thetelescoping rod, or alternately, it may be injected in one or moreinjection ports. The telescoping rod may also feature a resilient member236, such as a spring, within the rod to provide an expansive forcebetween the two portions of rod.

Referring now to FIG. 44 a, in a separate embodiment of the invention,the tension link 28 includes additional features that render itparticularly suited to implanting during a surgical operation. It isknown that a substantial number of implants involve the spanning orbridging of one vertebral disc. Therefore, one aspect of the presentinvention is to consecutively install the first and second attachmentdevices 10 with tension links 28 possessing extended shafts 30′.Specifically, the tension link 28 preferably is available in variablelengths. More preferably, the tension link 28 is long enough to provideeasy manipulation while being implanted. More preferably yet, thetension link 28 has an extended shaft 30′ that is substantially longerthan is necessary, but is capable of being trimmed during the surgicalimplanting procedure. Here, the tension link 28 with an extended shaft30′ may preferably be 10 to 150 millimeters longer than necessary, andmore preferably, 20 to 120 millimeters longer than necessary, and morepreferably yet 40 to 80 millimeters longer than is necessary.

The extended shaft 30′ is preferably used as a guide by the surgeon toprovide a means of placing the interior rod member 202 having receptacle100 and rod 54, clamp 200 including lower and upper clamp portions 204and 206 having securing ends 212 and 214, and link nuts 60. Accordingly,each extended shaft serves to guide the stabilizing structures to beimplanted. In use, the surgeon first installs the attachment device 10either with or without the tension link 28 already in place. If thetension link 28 is not installed concurrently with the attachment device10, the surgeon installs the tension link 28 after the attachment device10 has been installed. After installation of the attachment device 10and tension link 28, the extended shaft 30′ is used to guide theinterior rod member 202 possessing a receptacle 100 down to the enlargedarea 20 of attachment device 10. As a further example, the other tensionlink 28 with an extended shaft 30′ would serve to guide both clampportions of clamp 200. That is, lower clamp portion 204 and upper clampportion 206 with securing ends 212 and 214 are guided down to and placedover the end of the second attachment device 10. Thus, these componentsmay be slid down to the enlarged areas 20 of attachment devices 10 inone effort. Subsequently, tension link nuts 60 are slid down theextended shafts 30′ of tension links 28, and may be fully or at leastpartially threaded onto the threaded portions of shaft 30 of the tensionlinks 28. Subsequent to using the extended shaft 30′ as a guide to thehead of the attachment device 10, the extended shaft 30′ is trimmedusing a shearing tool familiar to those in the art, or the extendedshaft 30′ is broke along a pre-existing score 238, as shown in FIG. 44b. Thus, the extended shafts 30′ of the tension links 28 are preferablytrimmed by a surgical staff member, leaving a sufficient threadedportion in place to hold link nut 60. The extended shaft 30′ is thendiscarded, leaving the trimmed tension link shaft 30 in place with thelink nut 60 attached thereto. This embodiment offers the advantage beinga minimally invasive surgical procedure by providing means of performingspinal stabilization surgery, by supplying surgical implant devices andmethods that significantly limit the length of the surgical incision andthe length of time necessary to perform the surgery. Thus, benefits arerealized in the form of smaller incisions, less tissue displacement,less patient pain and recovery time, shorter surgical time, less cost,and less fatigue of surgical staff.

A further aspect of the above noted embodiment is the use of a flexibleextension or leader (not shown) on to the end of the shaft 30 of tensionlink 28. In this aspect of the invention, the substantially rigidportion of shaft 30 of tension link 28 is fitted with a relativelyflexible leader extending along the axis of the longitudinal axis ofshaft 30 of tension link 28. The flexible leader is preferably attachedto the tension link 28 sometime prior to surgery, and more preferablysometime during manufacture of the tension link 28. The flexible leaderthen serves to provide means of guiding any additional components downto the attachment device 10 as may be desired. The flexible leader ispreferably made of a material capable of being manipulated withoutbreaking during surgery. More preferably, the flexible leader is made ofa metallic wire material or a plastic material. More preferably yet, theflexible leader is easily separated from the end of shaft 30 of tensionlink 28 after any desired stabilizing components are installed.Accordingly, an extended tension link 28 may take the form of simply anextended shaft 30′, or it may take the form of a regular sized tensionlink 28 shaft 30 with a flexible leader attached thereto.

Other than the flexible leaders discussed above, the interior rod member202, lower clamp portion 204, upper clamp portion 206, rod 54,connectors 40, receptacles 100, attachment devices 10, tension links 28,and link nuts 60 and other structural features described herein are madefrom a material that possesses the appropriate strength characteristicsnecessary to withstand loading from the human body when used in medicalapplications. Tensile strength qualities of the materials used is a keyconsideration. Preferably, materials may include ceramics, plastics,metals, or carbon fiber composites. More preferably, the materials aremade from titanium or stainless steel.

Devices disclosed herein can also be made of thermal memory materials ormaterials that possess different elastic properties at varyingtemperatures. In this aspect of the invention, the subject component(s)may be heated or cooled to a desired temperature, implanted, thensubsequently allowed to cool or warm to the temperature of the ambientconditions that will exist during the usage period for the subjectdevice, namely, normal body temperature.

The dimensions of the rod features may vary considerably depending uponthe patient's needs. For example, a rod the entire length of the spine,such as 2 feet in length, may be used. Alternately, a rod only 10 mmlong may be all that is necessary to span and bridge the target segmentof the spine. Therefore, the preferable length of rod is simply anadequate length to bridge the necessary vertebral disc or discs.

The curvature of the rod may also be variable depending upon the desiredfinal curvature sought for the patient. The curvature may be establishedduring manufacture of a given rod, and/or a given rod segment may haveits curvature adjusted at the of time surgery prior to implantation.

While various embodiments of the present invention have been describedin detail, it is apparent that modifications and adaptations of thoseembodiments will occur to those skilled in the art. However, it is to beexpressly understood that such modifications and adaptations are withinthe spirit and scope of the present invention, as set forth in thefollowing claims.

1. A surgical implant assembly, comprising: an attachment device havingfirst and second ends, said second end having a hollow core bordered bycurved walls, said second end having a central aperture contiguous withsaid hollow core, said second end further including at least a secondopening wherein said second opening is at least one of an expansion slotand an entry channel; a tension link having a proximal end and a distalend, said proximal end having a tension link head and said distal endbeing threaded, said tension link head rotatably mounted within saidhollow core and maintained therein by contact with said curved walls;and a rod having at least one preformed socket adapted for at leastpartially receiving said second end, said socket including at least onetension link cavity, wherein said rod is secured to said attachmentdevice by a tension link nut that is threaded onto said distal end ofsaid tension link.
 2. The surgical implant assembly of claim 1, whereinsaid first end of said attachment device includes threads.
 3. Thesurgical implant assembly of claim 1, wherein said socket is at leastpartially spherical in shape.
 4. The surgical implant assembly of claim1, wherein said socket is located at an end of said rod.
 5. A method ofinstalling a surgical implant assembly, comprising the steps of: (a)securing an attachment device to human bone, the attachment devicehaving a shank with first and second ends, the second end having ahollow core and a central aperture, said second end further including atleast a second opening comprising an entry channel operatively connectedwith the hollow core; (b) inserting a tension link head of a tensionlink into the hollow core of the attachment device, the tension linkhaving a tension link shaft that extends through the central aperture ofthe attachment device; (c) seating a rod having a connecting receptacleonto the second end of the attachment device by passing the tension linkshaft through a tension link cavity within the connecting receptacle;and (d) securing the rod to the attachment device by threading andtightening a tension link nut onto the tension link shaft.
 6. The methodof claim 5, further comprising the step of adjusting an angularrelationship between the attachment device and the connectingreceptacle.
 7. The method of claim 6, wherein said adjusting step occursbetween steps (c) and (d).
 8. The method of claim 5, wherein saidinserting step further comprises inserting the tension link shaftthrough the entry channel and the hollow core, and pulling the tensionlink shaft through the central aperture until the tension link head ispositioned in the hollow core.
 9. A method of installing a surgicalimplant assembly, comprising the steps of: (a) securing an attachmentdevice to human bone, the attachment device having a shank with firstand second ends, the second end having a hollow core and a centralaperture, said second end further including at least a second openingcomprising an entry channel having an entrance operatively connectedwith the hollow core, and a tension link slot through the second end tothe hollow core between the entry channel and the central aperture; (b)inserting a tension link head of a tension link into the hollow core ofthe attachment device, the tension link having a tension link shaft thatextends through the central aperture of the attachment device, saidinserting step comprising placing the tension link head at the entranceof the entry channel, inserting the tension link shaft into the tensionlink slot such that the tension link shaft is located within the centralaperture, and pulling the tension link head into the hollow core; (c)seating a rod having a connecting receptacle onto the second end of theattachment device by passing the tension link shaft through a tensionlink cavity within the connecting receptacle; and (d) securing the rodto the attachment device by threading and tightening a tension link nutonto the tension link shaft.
 10. In subcombination, a low-profilemedical device connector used to connect a piece of hardware to a spine,the device used in combination with a tension link having a tension linkhead and a tension link shaft that threadably receives a tension linknut, and in combination with an attachment device having a substantiallyspherical shaped area with a hollow core for receiving the tension linkhead, a central aperture for passing the tension link shafttherethrough, and at least a second opening wherein the second openingis at least one of an expansion slot and an entry channel, saidconnector device comprising: a rod portion including a rod member foraligning substantially parallel to the spine and for at least partiallyspanning at least one disk of the spine, said rod portion furtherincluding a receptacle attached to said rod member, said receptacleincluding a substantially semi-spherical shaped socket adapted toreceive the substantially spherical shaped area of the attachmentdevice, said receptacle having a tension link cavity for passing thetension link shaft therethrough; wherein said socket is rotatable oversaid substantially spherical shaped area of the attachment device beforesecuring said rod portion to said attachment device, and wherein saidrod portion is secured to the attachment device by tightening thetension link nut on the tension link shaft after passing the tensionlink shaft through said tension link cavity upon placement of saidreceptacle over the attachment device.
 11. An attachment device adaptedfor use with a tension link, the tension link including a tension linkhead having a truncated area, the device comprising: a shank havingfirst and second ends, said first end having a securing mechanism, andsaid second end comprising a hollow core, an entry channel having atruncated surface, and a central aperture operatively associated withsaid hollow core and said entry channel; wherein said entry channel issized for receiving the tension link, and said cental aperture is sizedfor retaining the anchoring shaft head within said hollow core, andwherein the truncated area of the tension link head is substantiallyaligned with said truncated surface of said entry channel to insert orremove the tension link head from said hollow core.
 12. A connector asin claim 11, wherein said second end further comprises at least oneexpansion slot operatively associated with said central aperture.
 13. Aconnector device as in claim 11, wherein said securing mechanism isselected from the group consisting of screw threads, hooks, plates, andflanges.
 14. A connector device as in claim 11, wherein said hollow corehas an interior surface, said interior surface having a texture.
 15. Aconnector device as in claim 11, wherein at least a portion of thesecond end of said connector device has a shape selected from the groupconsisting of: spherical, semi-spherical, aspherical, polyhedral,conical, and a truncated cone shape.